CS 311 / MATH 352

1
CS 311 / MATH 352 Automata and Complexity Theory
2
Admistrative Stuff

• Instructor Shahab Baqai (baqai_at_lums.edu.pk) R
  oom 423, Ext 4423
• Lectures Mon Wed 1145 1325 hrs. A-15
• Tutorials As When needed
• Office Hrs Fri 1100 1300 hrs (or by
  appointment)
• TAs 2 Check course web for contact
  info and office hours etc
• Prerequisite CS211a - Discrete Mathematics I
• Website http//suraj.lums.edu.pk/cs311w07

3
Admistrative Stuff (cont.)
Questions We prefer that you post your question
to the class discussion form. The TA will try to
respond to all questions on the forum within 24
hours (48 hours Max). This way everyone gets the
benefit of reading the replies, and it helps to
reduce the number of repeat questions. For
questions that are not suitable to be posted to
the newsgroup (e.g. questions about your grade),
you can email your TA directly although there is
no guarantee of when you will receive a reply.
4
Course Organization
Text Book J. E. Hopcroft, R. Motwani, J. D.
Ullman Introduction to Automata
Theory,Languages, and Computation, Second
Edition,Addison-Wesley, New York,
2001. Instruments The 610 assignments, , 1012
quizzes, 01 midterm 01 final (will be
comprehensive). Weights Homework 0510 Quizz
es 1520 Midterm 3035 Final
Exam 4045
5
What we will do

• Automata abstract computing devices
• Turing studied Turing Machines (
  computers)before there were any real computers
• We will also look at simpler devices thanTuring
  machines (Finite State Automata, Pushdown
  Automata, . . . ), and specification means, such
  as grammars and regular expressions.
• NP-hardness what cannot be efficiently computed

6
Computation
memory
CPU
7
temporary memory
input memory
CPU
output memory
Program memory
8
Example
temporary memory
input memory
CPU
output memory
Program memory
compute
compute
9
temporary memory
input memory
CPU
output memory
Program memory
compute
compute
10
temporary memory
input memory
CPU
output memory
Program memory
compute
compute
11
temporary memory
input memory
CPU
Program memory
output memory
compute
compute
12
Automaton
temporary memory
Automaton
input memory
CPU
output memory
Program memory
13
Different Kinds of Automata

• Automata are distinguished by the temporary
  memory
• Finite Automata no temporary memory
• Pushdown Automata stack
• Turing Machines random access memory

14
Finite Automaton
temporary memory
input memory
Finite Automaton
output memory
Example Vending Machines
(small computing power)
15
Pushdown Automaton
Stack
Push, Pop
input memory
Pushdown Automaton
output memory
Example Compilers for Programming Languages
(medium computing power)
16
Turing Machine
Random Access Memory
input memory
Turing Machine
output memory
Examples Any Algorithm
(highest computing power)
17
Power of Automata
Finite Automata
Pushdown Automata
Turing Machine
Less power
More power
Solve more computational problems